Patients with active rheumatoid arthritis who have synovitis of the knee will be injected intra-articularly with rhu human IL-1 Receptor (rhy IL-IR) or a placebo control. Patients will be examined to determine the anti-inflammatory effect and the safety of IL-IR injected intra-articularly. Four groups of patients will be studied at escalating dosages of rhu IL-IR (25, 100, 250 & 500 micrograms). 3 patients will be injected with IL-IR at the lowest dose and 1 patient will be injected with diluant alone.